Digital portable media players can store large volumes of files, play music, display images and perform film clips using audio compression and video compression formats such as MP3, WMA, OGG, FLAC, MPEG-4, AA, ASF, MP4, AAC, JPEG, BMP, GIF, TIFF, PSD and PNG.
Some portable media players can be interfaced with audio or video systems in automobiles, for example, by coupling the analog audio output from a line-out or headphone-out jack to the vehicle media system (e.g., using a radio transmitter) or by connecting player's data port to the vehicle media system.
In another coupling arrangement, a cassette adapter is plugged into the portable device and inserted into a cassette deck in the vehicle, which picks up music from the player through the playback heads in the cassette deck.
Alternatively, a mini (3.5 mm) stereo headphone jack-to-stereo RCA cable or mini stereo-to-mini stereo cable can be connected between the line-out or headphone-out of the player and an auxiliary input of the vehicle media system, or in the absence of an auxiliary input, to a CD changer port.
Using a data port of the player as an interface to the vehicle media system may be done using a conventional Universal Serial Bus (USB) 2.0 or an IEEE 1394 FireWire 400 cable, or for some players a device specific adapter cable. Connecting the portable device using a USB or FireWire cable allows the portable device to be controlled by a CD interface or a head unit in the vehicle media system equipped with the drivers to support the USB or FireWire connection.
Microsoft's PlaysForSure® standard attempts to assure that a file compatible with the standard will be playable on a standard-compatible player without requiring multiple device-specific drivers.
Some vehicle media systems include data port portable device adapters that simulate CD changer functions, allowing users to move between and view track numbers in playlists and to skip between tracks using “Up” and “Down” arrows or play the contents of the portable device in “Random” mode.
Video players may be connected to a vehicle media system connecting a composite video and audio line out to a respective pair of connectors in the vehicle media system.